1. Field of the Invention
The present invention relates to an active matrix liquid crystal display device.
2. Description of the Related Art
Conventionally, an active matrix liquid crystal display device with an active element such as a thin film transistor (TFT) has been known. Since an active matrix liquid crystal display device can have higher pixel density as well as be small in size and low in weight and power consumption, products such as a monitor for a personal computer, a liquid crystal television, and a monitor for a car navigation system have been developed as one of flat panel displays in substitution for a CRT.
In a liquid crystal display device, display is conducted as follows: a substrate (an active matrix substrate), which is provided with a pixel portion including a first electrode (a pixel electrode) and the like in addition to a plurality of thin film transistors (TFT) and a wiring, and a substrate (a counter substrate), which is provided with a second electrode (a counter electrode), a light-shielding layer (a black matrix), a colored layer (a color filter), and the like, are attached to each other; a space between these substrates is filled with a liquid crystal and sealed; and liquid crystal molecules are aligned by an electric field which is applied between the pixel electrode and the counter electrode to control the amount of light from a light source.
When a liquid crystal display device displays an image, high-definition image display cannot be performed with uneven alignment of liquid crystal molecules. In order to evenly align liquid crystal molecules, a distance (cell gap) between a pixel electrode and a counter electrode is necessary to be the same (planarized). For example, as a method thereof, there is a method of forming an insulating film as a planarizing film by an application method or the like (Reference 1: Japanese Published Patent Application No. 2001-305576). An organic film described in Reference 1 is an organic insulating film for planarization, and it is an acrylic transparent organic film. As diagrams and the like show, when an organic film is used, a contact hole gets deep due to the thick thickness of the organic film.